The GNOME terminal program (gnome-terminal) is designed to emulate the 'xterm' program provided by the X Consortium. The 'xterm' program in turn is an almost-complete emulation of the DEC VT102 terminal.
The GNOME terminal program supports the same extensions to the VT102 that the xterm program provides, through special escape sequences. The xterm program is an evolving program. Recent changes to xterm have been been incorporated into gnome-terminal. This includes emulation of the newer DEC VT220 escape sequences.